1. Field of the Invention
The present invention relates to a graphic display method wherein the graphic processing or geometric modeling functions is effected, and more particularly to a graphic display method suitably applied to a system for supporting the designing of mechanical structures. The present invention also relates to a graphic display method for the geometry modeling of the mechanical structures design, and more particularly to an arrangement of the geometric model and display method suitably used to arrange and display an image on a graphic display apparatus.
2. Description of the Prior Art
Most of the conventional graphic display apparatuses having geometric modeling functions are adapted to handle three-dimensional figures, it is necessary that a party utilizing such a graphic display apparatus reduce the number of dimensions of object figures and transfer two-dimensional figure information constituting projection information to the graphic display apparatus. A similar process must be carried out every time the view data (position and view angle) change. This causes a loss in the response speed in a three-dimensional geometric modeling system.
In order to solve these problems, graphic display apparatuses having three-dimensional geometric modeling functions have been developed. A graphic display apparatus in which the hidden lines in a three-dimensional object formed of a large number of polygons are erased as disclosed in, for example, Japanese Patent Laid-Open No. 18745/1980 or U.S. Pat. No. 3,889,107 is known well.
In a method using this graphic display apparatus, only a three-dimensional object formed of a large number of polygons can be handled, and this graphic display method is not suitable used for design of a three-dimensional shape of a mechanical structure including a complicated curved surface. Although this graphic display apparatus is capable of describing a curved surface by a minute polygons, the amount of information becomes unduly large, and a long time is required for the transformation of this information.
Most of the conventional graphic display apparatuses of this kind are adapted to handle two-dimensional figures. In order to handle three-dimensional figures, it is necessary that the dimensional conversion be done in a graphic display apparatus, and a long time is required for carrying out the geometric modeling. There is a graphic display method in which a three-dimensional object is formed of a large number of polygons. However, when the polygons are made so as to represent a curved surface, the process time increases due to an increase in the amount of polygon data.
Various systems for supporting the design of a mechanical structure by using a computer have been developed, and various effects have been obtained. Such a system is used practically as a computer aided design (CAD) between a designer and a computer. During the use of this CAD system, the designer forwards his design as he makes interactions with the computer. This designing operation is always carried out with respect to the three-dimensional shape, and it is important that the three-dimensional shape thought by the designer can be inputted easily into the computer.
However, in the most popular conventional graphic display method used in such a system, already-determined numerical values are inputted into the computer by using a keyboard or fuction key, to thereby produce a three-dimensional shape in the calculating machine. Since a designer is accustomed to a drawing of a three-dimensional shape, it is easy for him to input the two-dimensional shape into the computer. Regarding such a shape, a two-view drawing method or a three-view drawing method are known, and drawing a three-dimensional shape by utilizing this drawing has also been practiced on trial. In this method, already-determined numerical values are also inputted into the computer.
There are some other known graphic display methods, which include a method using a three-dimensional coordinate reading machine based on photography or techniques using ultrasonic waves and laser beams, so as to input the information on an actual (physical) shape or a small-scale model (plastic model), if it is available, into the computer, and a method of inputting a model into the computer by using a graduated kit as disclosed in, for example, Japanese Patent Laid-Open No. 21227/1976.
In both of these methods, an already-available shape is inputted into the computer, but a three-dimensional shape drawn in the brain of the designer cannot easily be inputted. These conventional examples are the graphic display methods in which numerical values determined in advance are inputted into the computer by using the keyboard or function key.
The graphic display method using the three-dimensional coordinate reading machine in which photography or techniques using ultrasonic waves or laser beams as the information-intaking techniques, which are utilized when an actual model is available, is a method of inputting an already-existing three-dimensional shape, and not an inputting method of a shape drawn in the brain of the designer.